As is known, laryngoscopes are medical diagnostic instruments used to displace the tongue and epiglottis to permit a direct view of the larynx in the introduction of tracheal tubes during intubation, narcosis and other life-threatening situations.
Most laryngoscopes consist of a handle containing at least one battery used as a power source. A pivotable laryngeal blade assembly extends from an upper portion of the handle, the blade being pivotable to permit the blade to fold substantially flat against the handle for storage or to a deployed position for use thereof. Furthermore, the blade assembly is completely detachable from the handle.
At least two general types of laryngoscopes are presently known. In one version, the handle interior contains a miniature incandescent lamp and a bundle of optical fibers, defining a light pipe, guides illumination from the contained lamp to the distal end of the blade. According to a second version, a miniature lamp is not provided within the handle, but rather is disposed at the distal end of the light pipe. In each version, the light pipe is attached to the blade.
It is often desirable that the light pipe be removed from the laryngeal blade assembly to allow for cleaning, disinfecting, and sterilization.
It is a further desire to be able to remove the light pipe from the laryngeal blade assembly without the use of tools. For example, U.S. Pat. No. 4,958,624 to Stone et al. describes a light pipe assembly which is mounted to a laryngeal blade using a removable threaded fastener, requiring that a screwdriver or similar tool be utilized to effect disassembly. This removal procedure, given the totality of situations in which a laryngoscope can be used, can be both tedious and time consuming.
Another known instrument which is commercially available from Heine, Inc. of Germany includes a laryngeal blade having a light pipe assembly which releasably slides onto the blade in an axial direction; that is, the light pipe assembly is attached and released along the major dimension of the blade. A problem with this particular design is that the light pipe assembly may be prematurely ejected due to a sudden impact such as might occur if the blade were to be inadvertently dropped. It is also conceivable that the light pipe may also be prematurely ejected during assembly to the handle. Due to the urgency of use of these instruments in an operating theater, emergency room, or similar location, an inadvertent release of the light pipe assembly is obviously not desirable.
A second toolless version is described in a recently issued and commonly assigned U.S. Pat. No. 6,013,026 to Krauter et al., the entire contents of which are herein incorporated by reference. As described therein, according to a supporting block fixedly retains a light pipe. The supporting block includes a bore disposed in a direction which, when assembled to the blade assembly, is substantially perpendicular to the major dimension of the blade. A projecting engagement member of the blade engages the bore of the supporting block, the engagement member further including an undercut portion and an annular engagement member fitted within the undercut. When engaged together, the annular engagement member retains the light pipe within the laryngeal blade assembly until a predetermined holding force is exceeded.